This application is the national phase of international application PCT/EP99/09688 filed Dec. 9, 1999 which designated the U.S.
This invention relates to an arrangement for the connection of two rotor disks of an axial-flow turbomachine arranged one behind the other, more particularly two turbine rotor disks of an aero-engine, in which connecting arms protruding from the rotor disks essentially in the axial direction and facing each other are separably joined by way of several, pin-type fasteners, in particular bolts, distributed along the circumference. For background art, reference is made to Patent Specification DE 34 44 586 A1, for example.
For safety reasons, it is beneficial to provide a labyrinth seal between the two rotor disks of a two-stage high-pressure turbine of an aero-engine, for example, to prevent the hot gas passing across the blades of these rotor disks from entering the area between the rotor disks after whatever kind of failure of the total system. Such a labyrinth seal is realized in the aforementioned DE 34 44 586 A1 in the form of an arrangement termed xe2x80x9cmini-discxe2x80x9d (this being an additional, small intermediate disk).
Since the provision of such a labyrinth seal, for example in the form of the aforesaid mini-disc, will inevitably close off the area between the rotor disks to the outside, the required mechanical connection of the rotor disks must be made from the inside, i.e. from the rotational axis of the axial-flow turbomachinexe2x80x94with a separable bolted joint commonly being applied for this purpose.
In the prior art (and as demonstrated in the aforementioned Patent Specification DE 34 44 586 A1), the rotor disks are bolted together by a multitude of connecting bolts which extend in the axial direction of the turbomachine, said connecting bolts (or pin-type, separable fasteners in general) joining the two connecting arms protruding from the rotor disks essentially in the axial direction and facing each other. The circumferential connecting flange formed by the aforesaid connecting arms must be designed relatively stiff to account for the dynamic loads arising, this constraint resulting in relatively large geometrical dimensions. Furthermore, connecting bolts whose solidity is commensurate with this constraint must be provided. Since these connecting bolts or fasteners must moreover be installed, or threaded in, from the inside, the axial spacing of the two rotor disks is to be relatively large, this circumstance directly affecting the overall length of the axial-flow turbomachine or the aero-engine and increasing its mass unfavourably.
In a broad aspect, the present invention provides a remedy for the problems described above.
It is a particular object of the present invention to provide an arrangement in which the fasteners are essentially oriented in the radial direction, that is to say vertical to the axial direction. Further objects and advantages of the present invention are cited in the subclaims.
According to the present invention, the pin-type, separable fasteners, in particular the connecting bolts, extend essentially in the radial direction of the axial-flow turbomachine when they are provided or installed in the position in which they join the two connecting arms together, i.e. that said fasteners can simply be fitted or screwed in from the inside, that is to say from and vertical to the rotational axis, into the connecting flange formed by the two rotor disks. It is apparent that this radial orientation of the fasteners will allow for a considerably shorter axial distance of the rotor disks than in the case of an axial orientation of the fasteners.
It is apparent that appropriate bolt nuts or similar means must be provided on the rear side of the connecting flange when bolts are used as fasteners, but these nuts can be fitted suitably, preferably on one of the two connecting flanges, already before the assembly or the installation of the two rotor disks into the axial-flow turbomachine. In this context, it should be noted that the pin-type fasteners may also be fitted into the connecting flange radially from the outside if the space between the two rotor disks is accessible from the outside.